Bimetallic synergy boost TCPP(Ni)-Co MOF as the high-performance electrochemical sensor for enhanced detection of trace theophylline

Abstract

A bimetallic porphyrin MOF TCPP(Ni)-Co has been synthesized by the combination of reflux method and hydrothermal method. Due to the inherent conjugated ligand TCPP and the synergistic effect between metal center Co2+ and Ni2+, the TCPP(Ni)-Co MOF could work as the high-performance electrochemical sensor by the modification on the GCE. TCPP(Ni)-Co@GCE could realize the detection of trace theophylline with high sensitivity, fast response time (less than 3 s), detection range of 10–100 nM, and the extreme detection limit as low as about 3.3 nM. The good stability, repeatability and anti-interference performance further support TCPP(Ni)-Co MOF function as an excellent electrochemical sensor for theophylline. The enhanced detection mechanisms have been carefully discussed with X-ray photoelectron spectroscopy (XPS) and cyclic voltammograms (CVs) experiments. The coordination of Ni2+ in higher electron affinity could construct more electron-deficient environment in the well conjugate TCPP ligand, which could reduce the electron compensation to Co2+ in the formation of Co-COO coordination bond and set “Co-COO” in a higher oxidation state, thus enables TCPP(Ni)-Co MOF as the high-performance sensor for trace theophylline.